Ratite‐like neoteny induced by neonatal thyroidectomy of European starlings, Sturnus vulgaris

The Ratites (ostriches, emus, etc.) are thought to be neotenous descendants of flying birds, rather than primitive birds, even though they became a separate group early in the evolution of birds. This is because of the juvenile, rather than primitive, condition of the palate, skull‐sutures and feathers. We report here that European starlings (Sturnus vulgaris) thyroidectomized soon after hatching also show neoteny, retaining many juvenile features (general morphology, palate, skull‐sutures, feathers, behaviour), while at the same time becoming sexually mature. The juvenile characters were similar to those found in Ratites, suggesting that hypothyroidism may have been a factor in the evolution of the Ratites.